seminar presentation on continuously variable transmission CVT By Pukhraj Palariya

1. A SEMINAR PRESENTATION
ON
¥CONTINUOUSLY VARIABLE TRANSMISSION¥
(CVT)
Submitted from
Pukhraj mali
Roll no.:-12EELME035
ME Engg. final year
Submitted to
Mr.Rahul Shrivastav
Head of mechanical
department

2.  Today automobiles use either a conventional manual or
automatic transmission with multiple planetary gear sets that use
clutches to achieve discrete gear ratios .
 The continuously variable transmission replaces discrete gear
ratios with infinitely adjustable gearing through one of several
basic CVT designs
 A continuously variable transmission (CVT) is
a transmission that can change seamlessly through an infinite
number of effective gear ratios between maximum and minimum
values
 The flexibility of a CVT allows the input shaft to maintain a
constant angular velocity.
Introductionof CVT

3. Overviewof aCVT
Varies the transmission ratio continuously
Shifts automatically with an infinite number of
ratios.
Seamless power delivery
Constantly changes its gear ratio to optimize
engine efficiency
Allows the engine to rev almost immediately to
deliver maximum torque

4. Basicsof transmission
 The job of the transmission is
to change the speed ratio
between the engine and the
wheels of an automobile.
 The transmission uses a range
of gears to make more effective
use of the engine's torque as
driving conditions change.
There are 3 type of
transmission-
1.Manual transmission
2.Automatic transmission
3.Semi automatic(CVT)

5. PROBLEMS WITH MANUAL & AUTOMATIC TRANSMISSION
The traffic condition has become
annoying in our big cities so fuel
consumption is very high
 In such a case will automatic
transmission make sense to the Indian
customer.
 But conventional automatics always
consume slightly more fuel than manual
transmission and the lack of sophisticated
automatics.

6. Componentsof CVT
1. A variable –input driving
pulley
2. An output(driven) pulley
3. A metal belt/rollers
4. Sensors and microprocessors

7. Workingprinciple
 A pair of variable-diameter pulleys, each shaped like a pair
of opposing cones, with a metal belt or chain running between
them.
 One pulley is connected to the engine (input shaft), the other
to the drive wheels (output shaft)
 As the pulley halves come closer together the belt is forced
to ride higher on the pulley, effectively making the pulley's
diameter larger.
 Changing the diameter of the pulleys varies the
transmission's ratio.

8. HOWCVT WORKS?

9. Typesof CVT
Metal Push Belt CVT.
Toroidal Drive CVT.
Variable Diameter pulley Belt CVT
Hydrostatic CVT
 Magnetic CVT

10. Simulationof CVT
Push Belt
This belt transmits power between two
conical pulleys, or sheaves, one fixed and
one movable .
A sensor reads the engine output and
then electronically increases or decreases
the distance between pulleys, and thus the
tension of the drive belt

11. ToroidalTractionDriveCVT:
Uses rollers to transmit torque between the input disc and output
disc.
A viscous fluid transmits torque between rollers and discs.
Rollers and discs never touch.
The angle of the rollers changes relative to shaft position resulting
in a change in gear ratio.
The change in angle by a roller must be mirrored by the opposing
roller.

12. Toroidal CVT

13. ADVANTAGESOF CVT
 Decreases engine fatigue
 “infinite” number of gear ratios, maintaining
the engine in its optimum power range
 More mechanically efficient than Automatic
transmissions.
 Greater fuel efficiency than both manual and
automatic transmissions.(Fuel savings of more than
17%).
 Smooth, responsive and quiet to drive

14. CVTVs. Manual transmission
Theoretical comparison under “ideal”
conditions
1991 FIAT UNO
M=1250 KG,TORQUE=101.2 NM
0-100 KMPH
MT-11.9 SEC /CVT-8.8 SEC
CVT proved 35% more efficient
than the MT.
With same car and engine, the
CVT takes only 75% of the time
to accelerate to 100km/h,
compared to the MT.

15. DRAWBACKS
 Limited torque capacity when compared to
manual transmissions.
 Additional gear train required for reverse
condition.
 Larger and more costly than manual
transmissions.
 Unwillingness to discard billions of dollars
in development in MT & AT’s.

16. USESOF CVT
 Many small tractors for home and garden use have simple
rubber belt CVTs. For example, the John Deere Gator line of
small utility vehicles use a belt with a conical pulley system.
They can deliver an abundance of power and can reach
speeds of 30–32 mph (48–51 km/h), all without need for a
clutch or shifting gears. Nearly all snowmobiles, old and
new, and motor scooters use CVTs, typically the rubber
belt/variable pulley variety.
 In various ATV CVT is most widely used due to better fuel
economy.

17. The IC engine is nearing both perfection and obsolescence;
advancements in fuel economy and emissions have effectively
stalled.
CVTs could potentially allow IC vehicles to meet the first
wave of new fuel regulations
 Costs will be reduced further and performance will
continue to increase.
Ultimately it will give CVTs a solid foundation in the
world’s automotive infrastructure.
Future of CVT

18. THANK
YOU